D3 Examples - Multi-Series Line Chart

Multi-Series Line Chart - 4

This line chart is constructed from a TSV file storing the daily average temperatures of New York, San Francisco and Austin over the last year. The chart employs conventional margins and a number of D3 features:

d3.tsv - load and parse data

d3.time.format - parse dates

d3.time.scale - x-position encoding

d3.scale.linear - y-position encoding

d3.scale.category10, a d3.scale.ordinal - color encoding

d3.extent, d3.min and d3.max - compute domains

d3.keys - compute column names

d3.svg.axis - display axes

d3.svg.line - display line shape

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<!DOCTYPE html>
<meta charset="utf-8">
<style>
​
.axis--x path {
  display: none;
}
​
.line {
  fill: none;
  stroke: steelblue;
  stroke-width: 1.5px;
}
​
</style>
<svg width="960" height="500"></svg>
<script src="//d3js.org/d3.v4.min.js"></script>
<script>
​
var svg = d3.select("svg"),
    margin = {top: 20, right: 50, bottom: 30, left: 80},
    width = svg.attr("width") - margin.left - margin.right,
    height = svg.attr("height") - margin.top - margin.bottom,
    g = svg.append("g").attr("transform", "translate(" + margin.left + "," + margin.top + ")");
​
var parseTime = d3.timeParse("%Y%m%d");
​
var x = d3.scaleTime().range([0, width]),
    y = d3.scaleLinear().range([height, 0]),
    z = d3.scaleOrdinal(d3.schemeCategory10);
​
var line = d3.line()
    .x(function(d) { return x(d.date); })
    .y(function(d) { return y(d.temperature); });
​
d3.tsv("data.tsv", type, function(error, data) {
  if (error) throw error;
​
  var cities = data.columns.slice(1).map(function(id) {
    return {
      id: id,
      values: data.map(function(d) {
        return {date: d.date, temperature: d[id]};
      })
    };
  });
  
  console.log(cities)
  
  x.domain(d3.extent(data, function(d) { return d.date; }));
​
  y.domain([
    d3.min(cities, function(c) { return d3.min(c.values, function(d) { return d.temperature; }) - 5; }),
    d3.max(cities, function(c) { return d3.max(c.values, function(d) { return d.temperature; }) + 5; })
  ]);
​
​
  
  z.domain(cities.map(function(c) { return c.id; }));
​
  g.append("g")
      .attr("class", "axis axis--x")
      .attr("transform", "translate(0," + height + ")")
      .call(d3.axisBottom(x));
​
  g.append("g")
      .attr("class", "axis axis--y")
      .call(d3.axisRight(y).tickFormat(function(d) {return d + "º"}))
        .attr("transform", "translate(" + width + ",0)")
        .append("text")
      .attr("transform", "rotate(90)")
        
      .attr("y", 6)
      .attr("dy", "0.71em")
      .attr("fill", "#000")
      .text("Fahrenheit");
​
  
  var city = g.selectAll(".city")
    .data(cities)
    .enter().append("g")
      .attr("class", "city");
​
  city.append("path")
      .attr("class", "line")
      .attr("d", function(d) { return line(d.values); })
      .style("stroke", function(d) { return z(d.id); });
​
​
  city.append("text")
      .datum(function(d) {return {id: d.id, value: d.values[0]}; })
      .attr("transform", function(d) {return "translate(" + (x(d.value.date)-margin.left) + "," + y(d.value.temperature) + ")"; })
      .attr("x", 13)
      .attr("dy", function(d) {
          if (d.id == "San Francisco") {c = "1em";}
          else {c = "0.35em";}
          return c;
        }
      )
      .attr("dx", function(d) {
        if(d.id == "San Francisco") return ("0em");
        else if (d.id == "New York") return ("2.1em"); 
            else return ("3.6em");
      })
      .style("font", "10px sans-serif")
      .style("fill", function (d) { return z(d.id); })
      .text(function(d) { return d.id; });
​
   var minTemp = d3.min(cities, function(c) { 
     return d3.min(c.values, function(d) {
       return d.temperature; }); });
  
   var maxTemp = d3.max(cities, function(c) {
     return d3.max(c.values, function(d) {
       return d.temperature; }); });
    
  
        var i;
    for (i = 0; i < cities.length; i++) {
        var marks = city.append("g")
        .selectAll("circle")
        .data(cities[i].values)// fill in
        .enter();
​
      marks.append("circle")
        .attr("class", "circle")
        .attr("cx", function(d) {
          return x(d.date); //Returns original value bound from dataset
          })
        .attr("cy", function(d) {
            if(d.temperature < minTemp){
            minTemp = d.temperature;
          }
          if(d.temperature > maxTemp){
              maxTemp = d.temperature;
          }
          return y(d.temperature); //Returns original value bound from dataset
          })
        .attr("r", 2.2)
        .style("stroke", "white")
        .style("fill", z(cities[i].id));
      
      marks.filter(function (d) {return d.temperature == minTemp;})
       .append("text")
       .attr("x", function(d) {return x(d.date);})
       .attr("y", function(d) {return y(d.temperature);})
       .attr("dy", "1.2em")
       .attr("dx", "-1em")
       .style("font", "0.6em sans-serif")
       .style("fill", function (d) { return z(cities[i].id) })
       .text(function (d) {return d.temperature + "º";});
      
      marks.filter(function (d) {return d.temperature == maxTemp;})
      .append("text")
      .attr("x", function(d) {return x(d.date);})
      .attr("y", function(d) {return y(d.temperature);})
      .attr("dy", "-0.48em")
      .attr("dx", "-1em")
      .style("font", "0.6em sans-serif")
      .style("fill", function (d) { return z(cities[i].id) })
      .text(function (d) {return d.temperature + "º";});
    } 
    
​
  
  console.log(minTemp);
  console.log(maxTemp);
  
});
​
   
   
function type(d, _, columns) {
  d.date = parseTime(d.date);
  for (var i = 1, n = columns.length, c; i < n; ++i) d[c = columns[i]] = +d[c];
  return d;
}
​
</script>
    